There are many many outstanding suggestions here. I’m curious as to whether you are interested in wide overviews that hit most of the key dates and events, or more focused works on very specific parts of the conflicts.
Many of the examples here, while great reads, are the letter. A Bridge Too Far focuses on the preparations for and aftermath of one single campaign. The Longest Day focuses on D-Day, but neither one will give you a particularly wide historical sweep. Other books like Beach’s Submarine focus on a single military service.
For myself, I prefer these latter kinds of works, because they are more immediate can relate individual actions much more… intimately, I suppose. War memoirs also have that kind of personal impact, and I cans suggest numerous of them if that’s what you’re looking for.
But if you do want the historical sweep, you can’t do better than Shelby Foote’s Civil War series (it’s at least 3 volumes – been years since I read it). Samuel Elliott Morrison writes a fairly authoritative sweeping history of US participation in WWII, though I understand more recent scholarship has revised some of his narrative.
I’m gonna go against the grain here and advise against Stephen Ambrose. For one thing he was a relentless cheerleader for America, who it seems could do no wrong in his eyes. Then there are the many accounts of plagiarism, getting facts wrong and just making shit up. Read his Wiki page if you want more details.
FYI, another guy to avoid is David Irving, who wrote some reasonable histories before becoming a Holocaust denier. I’m not sure when he crossed the line into fruit bagdom – I read his biography of Rommel years back and thought it was pretty good, but now I have to suspect everything he’s ever written.